Conveyor screw apparatus



G. ALEXANDROVSKY CONVEYOR SCREW APPARATUS Oct. 2, 1962 Original FiledMarch 12, 1957 2 Sheets-Sheet l Smnentor $601666 flzamn/momswr Oct. 2,1962 G. ALEXANDROVSKY 3,056,533

CONVEYOR SCREW APPARATUS Original Filed March 12, 1957 2 Sheets-Sheet 23nnemor 62045: 4zzrmwaea rs/dr (Ittomeg 3,656,583 CONVEYOR SCREWAPPARATUS George Alexandrovsiry, Yonkers, N.Y. Cerro de Pasco Corp, 3%Park Ave, New York 22, NSY.)

Original application Mar. 12, 1957, Ser. No. 645,429, now

Patent No. 2,917,815, dated Dec. 22, 1959. Divided and this applicationMar. 23, 1959, Ser. No. 801,359

2 Claims. (Cl. 257-101) My invention relates to conveying screws havinghelical hollow flights. Such screws are being used either in conveyorsor other processing apparatus wherein the screw is mounted on a shaftrotating in a stationary trough or other container, or in tubularconveyors or processors wherein the screw is internally attached to oris integral vvith a rotating tube.

This application is a division of my copending application Serial No.645,429 filed March 12, 1957 (now Patent No. 2,917,815). Screws havinghollow flights are widely used in conveying and other processingapparatus where heat transfer is involved i.e. in operations where theprocessed a] material is to be cooled, or heated, or dried, or calcinedor the like, and where the heat exchange medium is to be completelyisolated from the processed material.

Conveying screws of the type described above are manufactured bypressing of prefabricated specially shaped metallic sheets; and they mayhave a hollow space in the screw flights which is separated from thehollow space in the shaft of the conveyor screw; as a result of whichthe heat exchange medium must flow through the conveyor in two separatecurrents and they are very expensive in manufacture and therefore theirapplication is quite limited.

It is an object of my invention to provide a conveying screw havinghelical hollow flights which avoid the disadvantages of the knownscrews, which is cheap in manfacture and which is particularly suitedfor use in tubular conveyor of the type referred to above.

The difference between the principle of my invention and that of knownconveyor screws is that the two hollow separated spaces, in the flightsand shaft of existing conveyor screws, require two currents of heatmedium whereas in my construction the space between the flights andhollow shaft communicate with each other to form a single uninterruptedspace, so that heat exchange fluid may flow as a single current throughthe conveyor screw.

The said and other objects of my invention will be more fully understoodfrom the following specification when read with the accompanyingdrawings.

In the drawings:

FIG. 1 is a front View of a conveying screw according to my invention;

FIGS. 2 and 3 show in front view two succeeding stages of said screwduring its manufacture;

FIG. 4 shows a front view of another embodiment of my new conveyingscrew for use in a rotary tubular conveyor;

FIGS. 5 to 7 show in front view three succeeding stages of said screwduring its manufacture;

FIG. 8 shows in front view the finished tubular conveyor (the outer tubebeing partially broken off); and

FIGS. 9 and 10 show in longitudinal sections the tubular conveyorattached, respectively, to two different means for supplying the heatexchange medium.

The conveyor screw shown in FIG. 1 is manufactured in the followingmanner:

A pair of metallic helical spirals 11, 12 of standard manufacture aremounted in spaced relation upon a tubular shaft 13 and are thereuponwelded or otherwise tightly attached thereto at their contacting edges14 as shown in 3,056,583 Patented Oct. 2, 1962 FIG. 2. It will beobserved in FIG. 1 that the distance between the pair of spirals 11, 12is less than half the length of the pitch of the spirals. Thereafter theportions 15 of the shaft 13 situated between said pair of spirals arevcut out for example by an oxygen flame. During the second manufacturingstage, illustrated in FIG. 3 a tubular cover 16 is placed over theassembly shown in FIG. 2, its portions 16 (shown in dotted lines)situated between the flights 12-11 are cut out leaving a spiral strip16" and the contacting edges 17, 18 are connected by welding or thelike, thus finishing the conveyor screw shown in FIG. 1. It will beunderstood that in said manufacturing operation the outer tube may becut into the spiral shape 16" shown in FIG. 3 before placing the sameover the assembly shown in FIG. 2, or that a sheet strip of spiral shapeconforming to the cut out spiral 16 may be used, and that also, ifdesired, the spiral section 15 may be cut out from the tubular shaft 13prior to attaching the helical spirals 11, 12 thereupon.

In the embodiment shown in FIG. 1 the liquid or gaseous heat exchangemedium is introduced .into the tubular shaft 13 and flows through thesame and the hollow screw flights formed between the spirals 11, 12 thuseflectively heating or cooling or drying the material to be processed.

Instead of closing the screw flights of the coordinated spirals 11, 12at their outer diameter by the strip 16" as shown in FIG. 1 the screwflights of coordinated,- spirals may be closed at their inner diameteras shown in FIG. 4 and in this form used in a rotary tubular conveyor ofthe type illustrated in FIGS. 8, 9 and 10. Such tubular conveyors aremanufactured as follows:

A pair of metallic helical spirals 21, 22 of standard manufacture aremounted in spaced relation upon a tubular member 23 and are thereuponwelded or otherwise tightly attached thereto at their contacting edges24 as shown in FIG. 5. Thereafter the portions 25 of the shaft situatedbetween the spirals 2221 are cut out leaving a helical strip 23'connecting the said spirals at their inner diameter (FIG. 6). It will beobserved in FIG. 5 that the length of portion 25 is more than half thelength of the pitch of the spirals 21, 22. Thereupon a tubular body, 26is placed over the assembly shown in FIG. 6, its portions 26' betweenthe spirals 21-22 are cut out as illustrated in FIG. 4 and thecontacting edges 27, 28 are tightly connected by welding or the likethus shaping a hollow spiral closed at its inner diameter and open atits outer diameter. It will be well understood that in saidmanufacturing operation the outer tube 26 and/or the tubular member 23may be either cut into the required spiral shape before attaching thesame to the spirals 21, 22, or may be replaced by a sheet strip ofspiral shape.

The assembly shown in FIG. 4 is then placed centrally into the rotaryconveyor tube 29 and firmly attached thereto by distancing means such asmetal plate 30 or the like. The ends of the conveyor tube 29 may beeither, as shown in FIG. 9, rotatably and tightly mounted in a frontcontainer 3 1, and a rear container 31a, the heat exchange medium beingsupplied from one and emptied into the other container after havingflown between the conveyor tube 29 and the conveying screw as well asthrough the hollow helical channels 36 thereof. Alternatively as shownin FIG. 10 the tube 29 may be closed at each end by a cover cap 32 andthe heat exchange medium introduced by an inlet pipe 33 through a unionconnection 34 and let out at the other end of the con veyor tube (whichis not shown) by a corresponding outlet pipe. In FIG. 10 the inner spaceof the conveyor screw is closed at each end against the flow of the heatexchange medium by tightly mounted cover plates 35. For introducing feedinto the conveyor more particularly into the inner space of the conveyorscrew thereof a conventional feeder is attached at or near to itsforward end. Such a conventional feeder arrangement is shown in FIG. 9.A conduit 37, extending through the wall 38 of container 31 is rotatablein a bearing 39 and the tube 29 is rotatable in bearing 40. This feedconduit 37 :leads into the interior of the hollow screw. The inner endof the conduit 37 is secured to the end of the hollow screw inconventional manner so that the screw and the feed conduit rotatetogether. The rear end container 31a is of similar conventionalconstruction as the front end container 31 so that material fed throughconduit 37 passes through the hollow screw and is discharged throughconduit 37a which rotates in a bearing 39a; the tube 29 rotating inbearing 40a. The heat exchange medium is introduced through container 31and is exhausted through rear container 31a after passing through thetube 29. Conventional means for rotating the tubular conveyor may 'beemployed; such as ring gear 41, secured to the periphery of tube 29,meshing with pinion 42, which in turn is driven by a motor 43.

While specific embodiments of my invention have been shown and describedin detail to illustrate the application of the principles of myinvention, it will be well understood that the same may be otherwiseexecuted and embodied without departing from such principles.

What is claimed is:

1. In a rotatable tubular screw conveyor apparatus, an outer rotatablecylindrical conveyor tube, a hollow conveyor screw through which hotsolids may be conveyed, said hollow screw being fixedly mountedcoaxially and concentrically within said outer tube and rotatable inunison with said outer tube, feed mean to supply hot solids to theinterior of said hollow screw at its front end and discharge means todischarge hot solids from the rear end, said conveyor screw comprising afirst coaxial helical strip and a second coaxial helical strip arrangedin parallel relation providing a pair of coaxial helical stripsequidistant apart through their lengths, said pair of helical stripsbeing substantially transverse of the axis of rotation of said screw andhaving helically shaped inner edges and helically shaped outer edges, aninner tubular helical strip having oppositely disposed helical shapededges, one edge of said inner tubular helical strip being tightlyconnected with the inner helical edge of said first helical strip andthe other of said helical edges of said inner tubular helical stripbeing tightly connected with the inner helical edge of said secondhelical strip, an outer tubular helical strip having oppositely disposedhelically shaped edges, one of said edges of said outer tubular helicalstrip 'being tightly connected to the outer helical edge of said firsthelical strip and the other of said edges of said outer tubular helicalstrip being tightly connected to the outer helical edge of said secondhelical strip, said inner, tubular helical strip lying in the helicalarea inside the inner edges of said pair of first and second helicalstrips, said inner tubular helical strip together with said pair f firstand second helical strips defining a helical channel communicating withthe interior of said tube along the entire length of said hollow screw,said outer tubular helical strip lying in the helical area outside theouter edges of said pair of first and second helical strips, a pluralityof longitudinally and circumferentially spacedspacer-elements secured tothe interior surface of said outer tube and to the outer surface of saidouter tubular helical strip of said hollow conveyor screw and fixedlymounting said screw within said outer tube in a position which providesan annular space of substantial radial length between the inner surfaceof said outer tube and the outer surface of said outer tubular helicalstrip along the entire length of said tubular helical outer strip, saidhelical channel communicating along the entire length of said screw withsaid annular space, said helical channel and communicating annular spaceproviding passageway for fluid heat-exchange medium through which thesaidi fluid medium may pass in a single undivided stream from one end ofsaid tube to the other to effect contact of the liquid heat-exchangemedium with the total area of said helical channel and the total area ofsaid outer tubular helical strip as the heat-exchange medium passesthrough said tube, means positioned at each end of said conveyor tubehaving supporting means for rotatably and tightly mounting said tube atboth of its ends; means for introducing heat exchange medium into saidannular space in said tube, means for discharging said heat exchangemedium after it has passed through said annular space, and means forrotating said tube together with said hollow 2. A rotatable tubularscrew conveyor apparatus constructed according to claim 1 in which theouter tubular helical strip has a coaxial width more than half the pitchof said pair of first and second helical strips and the inner tubularhelical strip defines the width of said helical channel and has acoaxial width less than half the pitch of said pair of first and secondhelical strips.

References Cited in the file of this patent UNITED STATES PATENTS

